Volume 47, Issue 1, Pages 5-15 (July 2012) mRNA Decay Factor AUF1 Maintains Normal Aging, Telomere Maintenance, and Suppression of Senescence by Activation of Telomerase Transcription  Adam R. Pont, Navid Sadri, Susan J. Hsiao, Susan Smith, Robert J. Schneider  Molecular Cell  Volume 47, Issue 1, Pages 5-15 (July 2012) DOI: 10.1016/j.molcel.2012.04.019 Copyright © 2012 Elsevier Inc. Terms and Conditions

Figure 1 Decreased Survival and Increased Markers of Aging in Late-Generation Auf1−/− Mice (A) Percentage of each genotype at live birth from Auf1+/− crossings for indicated generation. n = number of mice in each group. p values based on expected Mendelian ratios, n = 3. ∗p ≤ 0.04; ∗∗p ≤ 0.02, calculated by Chi-square test. (B) Frequency and survival beyond 4 weeks for Auf1−/− KO mice per generation. (C) Top: Representative images of whole testes from 25-day-old G7 WT (Auf1+/+) and KO littermates. Bottom: H&E sections showing aberrant maturation and degeneration of germ cell epithelium (yellow arrowhead). (D) Representative images of SA-β-gal staining, a marker for cellular senescence, in indicated tissues from 2-day-old WT and KO littermates. (E) Staining for SA-β-gal in the villi of the duodenum and white pulp of the spleen from 12-month-old mice. (F and G) Proliferation of isolated splenic CD3+ T cells and B220+ B cells by 3H-thymidine labeling of G6 animals. ∗p < 0.01 by paired Student's t test ± SEM, n = 3. (H) Frequency of live births and survival of G7, G5.BC1.iG1, and G5.BC1.iG2 KO mice. Molecular Cell 2012 47, 5-15DOI: (10.1016/j.molcel.2012.04.019) Copyright © 2012 Elsevier Inc. Terms and Conditions

Figure 2 Aging-Related Phenotypes and Upregulation of p16Ink4A, p19Arf, and p21CIP Expression in Auf1−/− Mice (A) Representative images of kyphosis (hunchback) (arrow), presence (top panel) and absence (bottom panel) of subcutaneous body fat (arrows), and atrophied gonads typically observed in 12-month-old Auf1−/− (KO) mice but not in WT littermates. Images shown represent the majority of KO animals surveyed (>60%, kyphosis; >90%, reduced body fat; >90%, gonadal atrophy). (B) Increased relative expression of p16Ink4a, p19Arf, and p21CIP mRNAs in tissues and organs from 12-month-old KO mice compared to WT littermates, determined by qRT-PCR. (C) Immunohistochemical staining for p16Ink4a and p21CIP (brown, arrows) in organ sections from 12-month-old KO mice compared to WT littermates. Sections counterstained by H&E. (D) Decay plots of p16Ink4a, p19Arf, and p21CIP mRNAs in MEFs from G2 embryos. Transcription was blocked with actinomycin D, cells were collected at indicated time points, RNA was extracted and mRNA levels were quantified by qRT-PCR. Plots are the mean of three independent experiments with calculated half-lives shown. (E) Decay plots showing recovery of p16Ink4a mRNA destabilization by individual isoforms of AUF1 in KO MEFs. Plot shown is an average of three independent experiments. Molecular Cell 2012 47, 5-15DOI: (10.1016/j.molcel.2012.04.019) Copyright © 2012 Elsevier Inc. Terms and Conditions

Figure 3 Decreased Telomere Lengths in Late-Generation Auf1−/− Splenocytes (A) Q-FISH telomere length analysis, frequency distribution of telomeric DNA signal intensities (telomere fluorescence units, TFUs), ≥20 metaphase splenocyte spreads of three mice. Arrow, chromosome ends with no detectable telomere (signal free ends, SFEs), ∗p < 0.01. (B) Left, representative splenocyte metaphase spreads from G7 mice stained with Cy3-labeled PNA telomere probes (arrows, SFEs). Right, frequency of SFEs in G7 splenocyte metaphase spreads. ∗p < 0.05, ± SEM, n = 3. (C) Left, chromosomal abnormalities in KO spreads: representative fused chromosomes (yellow), chromosomal breaks (green), uneven translocated chromatids (red). Right, frequency of end-to-end fusions in G7 splenocyte metaphase spreads, ≥150 metaphase spreads from three mice each, ± SEM. (D) Frequency of SFEs in splenocyte metaphase spreads from G7 mice and corresponding mice from single WT backcrossed (G5.BC1.iG1) or triple WT backcrossed (G5.BC3.iG1) backgrounds. Values are mean ± SEM (n = 4). ∗p < 0.05. All statistics by paired Student's t test. Molecular Cell 2012 47, 5-15DOI: (10.1016/j.molcel.2012.04.019) Copyright © 2012 Elsevier Inc. Terms and Conditions

Figure 4 Increased DNA Damage Signaling at Telomere Ends and Cell Growth Defects in Auf1−/− Cells (A) Levels of phospho-ATM (arrowhead), phospho-p53 (Ser15), and p21CIP determined by immunoblot analysis in two independent AUF1 WT and KO MEF cell lines. (B) Immunofluorescence staining for γ-H2AX and TRF1 colocalized at telomere ends. Arrowheads: telomere dysfunction induced foci (TIFs) (Takai et al., 2003). (C) Quantification of TIFs in MEFs from indicated generation, ≥30 nuclei from three MEF cell lines. Positive cells contain ≥ 5 TIFs. Values are mean ± SEM (n = 3). p < 0.01 by paired Student's t test. E, early passage; L, late passage. (D) MEF proliferation determined by MTT assay. E, early passage; L, late passage; PD, population doublings. Values are p < 0.01, ± SEM, n = 4. (E) Anchorage-independent growth assayed by soft agar colony formation. Number of colonies shown. (F) Representative end-to-end chromosomal fusions lacking detectable telomere signal (arrow) in AUF1 KO splenocyte cell metaphase spreads stained with telomere-specific probes and DAPI counter-stained. Molecular Cell 2012 47, 5-15DOI: (10.1016/j.molcel.2012.04.019) Copyright © 2012 Elsevier Inc. Terms and Conditions

Figure 5 Strongly Decreased Telomerase Levels and Activity in AUF1-Deficient Cells (A and B) Relative mTert and mTerc RNA levels in WT and AUF1 KO MEFs, determined by qRT-PCR. ∗p < 0.05 ± SEM, n = 3. (C) Immunoblot showing mTERT protein levels in WT and KO MEFs. (D) Relative telomerase activity in extracts from WT and KO MEFs as determined by TRAP assay. Mean ± SEM of three independent experiments, ∗p < 0.05. (E) Partial rescue of mTert mRNA expression in AUF1−/− (KO) MEFs by ectopic expression of individual AUF1 isoforms, determined by qRT-PCR. Representative immunoblot for AUF1 is shown. The p37 AUF1 panel was exposed 3× longer. (F) Rescue of mTERT mRNA expression by p45/p42 AUF1 isoforms in AUF1 KO MEF cells, carried out as described above. ∗p < 0.05 ± SEM (n = 4). (G) Telomere restriction fragment analysis of serially passaged KO MEF cells with or without ectopic mTERT expression. Autoradiograph indicates intensity of probe-hybridization to specific telomeric sequence. Typical results shown of three studies. Average telomere fragment length is indicated below. ∗p < 0.05 by Student's t test, n = 3. Molecular Cell 2012 47, 5-15DOI: (10.1016/j.molcel.2012.04.019) Copyright © 2012 Elsevier Inc. Terms and Conditions

Figure 6 AUF1 Stimulates mTERT Transcription (A) Nascent mTert transcript levels determined by intron-exon qRT-PCR. ∗p < 0.05. Error bars represent the SEM from three independent experiments. (B) Decay rates of mTert and mTerc RNAs. Plots are the average of three independent experiments. (C) Promoter regions of mTert, mTerc, IL-6, and Tk1 genes were detected by semiquantitative PCR from input and AUF1-bound immunoprecipitated chromatin samples from WT and KO MEFs. Representative negative images from ethidium-bromide stained agarose gels are shown. (D) Promoter-coupled luciferase constructs in WT and KO MEFs from mTert expression. Firefly luciferase activity was normalized to Renilla luciferase activity of a cotransfected null-promoter plasmid. Length of mTERT promoter in each construct is indicated. ∗p < 0.05, ± SEM. Molecular Cell 2012 47, 5-15DOI: (10.1016/j.molcel.2012.04.019) Copyright © 2012 Elsevier Inc. Terms and Conditions